The following meanings for the abbreviations used in this specification apply:
CN core network
D2D device-to-device
eNB enhanced node B
eNodeB enhanced node B
EPC evolved packet core
EPS evolved packet system
EUTRAN Evolved Universal Terrestrial Radio Access Network
ID identification
LTE Long Term Evolution
LTE-A LTE Advanced
MAC medium access control
MME mobility management entity
PLMN public land mobile network
RB radio bearer
RRC radio resource control
S-GW service gateway
SIB system information block
SRB signalling radio bearer
UE user equipment
UL uplink
In the last few years, an increasing extension of communication networks, e.g. of wire based communication networks, such as the Integrated Services Digital Network (ISDN), DSL, or wireless communication networks, such as the cdma2000 (code division multiple access) system, cellular 3rd generation (3G) communication networks like the Universal Mobile Telecommunications System (UMTS), enhanced communication networks based e.g. on LTE, cellular 2nd generation (2G) communication networks like the Global System for Mobile communications (GSM), the General Packet Radio System (GPRS), the Enhanced Data Rates for Global Evolutions (EDGE), or other wireless communication system, such as the Wireless Local Area Network (WLAN), Bluetooth or Worldwide Interoperability for Microwave Access (WiMAX), took place all over the world. Various organisations, such as the 3rd Generation Partnership Project (3GPP), Telecoms & Internet converged Services & Protocols for Advanced Networks (TISPAN), the International Telecommunication union (ITU), 3rd Generation Partnership Project 2 (3GPP2), Internet Engineering Task Force (IETF), the IEEE (Institute of Electrical and Electronics Engineers), the WiMAX Forum and the like, are working on standards for telecommunication network and access environments.
Recently, so-called “proximity-based” applications and services came into the focus of further developments in the field of telecommunications. The term proximity-based applications and services may be used, for example, in cases where two or more devices (i.e. two or more users), which are close to each other, are interested in exchanging data, if possible, directly with each other. Currently, such “proximity-based” applications operate fully “over the top” and are based on “high-level software”, typically relying on a mix of GPS location and of the 3GPP mobile systems used as “data pipes”.
However, such an approach presents fundamental technology limitations from the point of view of e.g. device battery life (due to the extensive GPS usage), signalling load to the network (due to the required uplink bursty traffic) and simplicity (due to the “proactive” behaviour required of the user, e.g. the “check in”).
While the use of an unlicensed-spectrum communication can address some of the aspects mentioned earlier, it still presents some limitations. For example, discovery processes are being defined based on direct message exchanges which are thus not optimal for operation over longer ranges (hundreds of metres or more), or preserve a reasonable battery life. For the same reason, an unlicensed option cannot be expected to scale among a large number of devices.
For future cellular communication networks, a possible method for such proximity-based applications and services is the so-called device-to-device (D2D) communication. D2D offers a high communication speed, large capacity and a high quality of service, which are important features to be achieved. Advantages achievable by the implementation of D2D communications in the cellular communication environment are, for example, an offloading of the cellular system, reduced battery consumption due to lower transmission power, an increased data rate, an improvement in local area coverage robustness to infrastructure failures and also an enablement of new services. This is possible while also providing access to licensed spectrum with a controlled interference environment to avoid the uncertainties of license exempt band. Due to this, D2D communication gains more and more attraction and interest.
However, in order to make D2D communication feasible in communication networks, such as those based on 3GPP LTE systems, it is necessary to provide a fast and efficient mechanism for requesting access to D2D services.
Embodiments are directed towards providing an improved method of requesting access to D2D services in communication networks.